ABSTRACT
Although severe coronavirus disease 19 (COVID-19) and hospitalization associated with COVID-19 are generally preventable among healthy vaccine recipients, patients with immunosuppression have poor immunogenic responses to COVID-19 vaccines and remain at high risk of infection with SARS-CoV-2 and hospitalization. Additionally, monoclonal antibody therapy is limited by the emergence of novel SARS-CoV-2 variants that have serially escaped neutralization. In this context, there is interest in understanding the clinical benefit associated with COVID-19 convalescent plasma collected from persons who have been both naturally infected with SARS-CoV-2 and vaccinated against SARS-CoV-2 (vax-plasma). Thus, we report the clinical outcome of 208 immunocompromised outpatients who were diagnosed with COVID-19 and who received contemporary COVID-19 specific therapeutics (standard of care group) and a subgroup who also received concomitant treatment with very high titer COVID-19 convalescent plasma (vax-plasma group) with a specific focus on hospitalization rates. The overall hospitalization rate was 1% (1 of 123 patients) in the vax-plasma group and 6% (5 of 85 patients) in the standard of care group, which corresponded to a relative risk reduction of 83%. Evidence of efficacy in nonvaccinated patients cannot be inferred from these data because 94% (196 of 208 patients) of patients were vaccinated. In vaccinated patients with immunosuppression and COVID-19, the addition of vax-plasma or very high titer COVID-19 convalescent plasma to COVID-19 specific therapies reduced the risk of disease progression leading to hospitalization.